The invention relates generally to latching switch mechanisms and more particularly to a switch mechanism for a compact light emitting diode (xe2x80x9cLEDxe2x80x9d) flashlight device.
During the past few years, the brightness of LED technology has improved to allow for their use in small personal flashlight devices. Many of these devices are simply packaged in plastic housings utilizing momentary switches, and are meant to be disposable once the battery source is depleted. One example of this is the ADVA-LITE(trademark) Tag Lite. The use of lithium xe2x80x9ccoin cellxe2x80x9d batteries, such as the EVEREADY(trademark) CR2032, as a power source, has improved the state of the art of these miniature flashlight designs. Such coin cells are of relatively high voltage (e.g., 3 volts), compact, inexpensive, and reliable ( greater than 5 year storage life). Most, if not all, of these devices utilize a switch design which places the LED bi-wire leads across each polarity of the coin cell battery. One LED wire lead continually contacts its corresponding battery surface, while a means is provided to press the opposite LED wire lead against the corresponding battery surface to activate the circuit. The spring tension in the wire lead or a foam button are the usual means used to return the circuit to an off condition. In U.S. Pat. No. 5,893,631 to Padden (Apr. 13, 1999), a plastic spring that is integral to the coin cell carrier is used to return the circuit to an xe2x80x9coffxe2x80x9d condition.
Because the LED component is very reliable (50,000-100,000 hours), the state of the art has changed to provide a means for replacing the depleted power source. Another improvement has been the use of xe2x80x9clatch-onxe2x80x9d type of switch mechanisms so as to free up the users hands while using the flashlight. An example of this is the PHOTON MICROLIGHT II(trademark) of L.R.I., of Blachly, Oreg., U.S.A. (see, e.g., U.S. Pat. No. D375372 to Allen (Nov. 5, 1996)).
As in the case of the PHOTON MICROLIGHT II(trademark) product, an effort has been made to create a low-cost manufacturable design which requires the use of the LED biwire leads to surround the coin cell. One LED wire lead continually contacts its corresponding battery surface while a means is provided to press the opposite LED wire lead against its corresponding battery surface to activate the circuit.
The current state of the art using a LED, coin cell, and LED wire leads as key components of the switch mechanics, leads to a difficulty in replacing the battery source. As in the case of the PHOTON MICROLIGHT II(trademark) product, four #0 screws are removed and the entire assembly dismantled to change the coin cell. All of the components are then reassembled properly to assure the flashlight will operate again. Padden""s design (U.S. Pat. No. 5,893,631) is simpler in that the battery carrier can be removed to replace the cell, but in this example, it is still a momentary switch design. Another aspect of this type of switch design is that the wire lead could potentially be damaged through metal fatigue due to the bending action. The manufacturing standard for most if not all LEDs is to use tin plated steel wire leads.
In summary, none of the current state of the art in LED flashlights is believed to contain both a convenient means of changing the power source along with a latching switch mechanism.
The invention describes a very compact flashlight with a latching switch and means to easily change the battery storage. The lamp is a standard flanged LED which has bifurcated electrical leads. The lamp is centered at one end in an injection molded plastic housing which comprises two parts fastened to form a vessel. One end of the vessel has an aperture to allow the light emitting end of the lamp to pass therethrough. Within the vessel base are cylindrically shaped saddles for the lamp to set in and rotate upon. Also within the vessel are protruding cylindrically shaped walls to constrain the coin cell battery which sits between the bifurcated LED leads. The vessel also has additional apertures for the passing through of the gripping protuberance of the switch cam and an aperture for changing the coin cell battery. A cam made of electrically nonconducting plastic and formed with two through holes is assembled to the LED by sliding it over the LED""s bifurcated leads. The LED leads are then bent to fasten the cam to the LED but also to provide a minute clearance for the leads to surround the anode and cathode surfaces of the coin cell. The perimeter of the cam has two mechanical features to form a gripping protuberance and a lobe for locking the cam in one of two positions. The LED lead clearance around the coin cell battery is an improvement in that neither lead needs to be touching the anode or cathode surfaces of the battery in the off condition of the light which is a requirement for momentary switches in LED flashlight designs. In addition, the LED lead clearance also allows the coin cell to be readily replaced without total disassembly of the flashlight. A small plastic interlocking panel closes the side aperture to the flashlight to final constrain the coin cell. The interlocking panel can be removed by a simple prying motion on one edge so that a fresh coin cell can be exchanged for the depleted one.
To illuminate the flashlight, one pushes on the cam""s protuberance grip, thereby imparting a rotational motion on the LED and its bifurcated leads. Upon rotation, the bifurcated leads come into contact with their respective anode and cathode surfaces of the coin cell illuminating the LED. As the cam continues to rotate, a lobe on the cam starts to pass through the vessels aperture. A deflection, consisting of the upper vessel wall and clearances around the LED saddles and LED, occurs, allowing the lobe to pass through the aperture and over center the cam. The cam""s lobe shape transitions to a flat surface as the lobe passes through the vessel aperture, resting against its corresponding aperture side wall and temporarily latches the cam into position thus maintaining the bifurcated LED lead contacts to the coin cell. Residual spring tension in the LED leads provides sufficient contact pressure to sustain electrical current flow between the coin cell and LED leads while maintaining back pressure on the cam. By reversing the cams rotation, the cam""s lobe once again passes through the aperture, switching and latching the flashlight off.
The invention provides a latching switch mechanism for LED flashlights while maintaining an easy means of changing battery storage by rotating a LED of biwire design such that the anode and cathode leads contact their corresponding surfaces of a coin cell battery.
The invention also provides a circuit in which neither wire lead from a bifurcated lamp needs to continually maintain contact with the power source while in the off condition.
Equally important, the invention provides a switch mechanism that latches the circuit on, so as to free the flashlight users hands.
The invention also provides a flashlight switch and assembly that are inexpensive to manufacture.
The invention also provides a personal flashlight with multiple uses by maintaining a planar surface on one side of the flashlight casing so that the device can be stabilized on a surface or so that attaching mechanisms can be added. Attaching mechanisms can be devices such as magnets, VELCRO(trademark) (hook and loop fastener) or adhesive.
The invention also can provide a personal flashlight with multiple uses by providing a hole through the flashlight casing for a lanyard or loop attachment.